Preparation of odorless fractions of highly branched paraffins



y 1949. H. LEGATSKI ET AL 2,468,986

I PREPARATION OF ODORLESS FRACTIONS OF HIGHLY BRANCHED PARAFFINS FiledSept. 17, 1945 END PoINT 350F aso 4oo F" END POINT 475F Y r; N

END POINT 525F s2sr I I d) I l I INVENTORS. H. R. LEGATSKI C.C. CRAWFORDBY ZEYs h MIXED ALKYLATES ATT \ THa-rold :Legastkiand 'Ghester C.GraWfor d,

-.:Ian\olefin:are reactantsand in processes for t'he late -inthepresence of solid caustic, percolating -m a d s pyl ns d rabe'quanti- :10 the distillate' through fuller s earth. None :of ties ofalkylates which have boiling :rangestoverthese processes have yieldeda-pro'duct having flapping and above the =motor fuel range are ob- "odorcharacteristics 'necessary in a solvent mer- 'tained as iby-produ'cts.'When itisattemptedtto chantable to theabove-mentioned industries."irac'tionally distill these by -products into fra-c- "The reactionsbywliich odorous compoundsare "tions of 'suitable' boilin range 'foruseassolvents l5 "formedduring suchflistillation or-agingare-not i rv n n pin i s-p in nd -insecti- "completely understood but it is believed 'thatcities 'it is found thatthe odors of :theral-kyl-ate such--reactions-are *due to the large number-of .'-fractions obtained by theusual p 'o'c s OfrdiS- secondary and/or tertia-ry carbon atoms present.tillation make them'unfit "for use in the above Itis knownthatolefinformationis not the cause acommercial applications. so ofodori-nthedistillate sincethe bromine number ithe d y cleaning, vpaint a d ncticid :in- "Ofthe hydrocarbon is'not increasedby distillation. dustriesodors of solvents are especially objectiont is'a principal object'of ourinvention 'to proable. If alkylate fractions are to' loe usold to videa'method fonseparating mixture 'of highly these industries thefractionsmustnot :only have branched -parafiin hydrocarbons, =boiling-"at" temq red solventp perties:andhoil ngaran ze peratures above, butpartially -overlapping *the *but mus be 'ab "t o p' fully with -motorfuel rangesinto'fractions of desired. boiling tdeodorizedrstraight:runnaphthas :on theabasiszof range which *haVe'-'s0"litt1e odor "as to 'besuitable -odor. "for use as solvents in paints; insecticides and inThe-synthetic, :branchedechain paraffin hydrow a cleaning-art, fl y c tlyt processes .isuch ::as 30 *Numerous other objectsan'dfeatures- 'ofnovelty id ylation, or'polymerization of olefins followed ---willbecomeapparent to those skilled in the :art by hydrogenation; arehydrocarbonshavingccharas this disclosure; proceeds. vmcteristically:very low =:odor-:intensity. ."Itzis 'com- (our invention consists of'the unexpected dis- "mon'cpracti'oe "the manufacture :df ithesezcom-"covery that'while the odorous eompounds'formed ,lccatalyst life. fSuchpurification o "feed' stocks- 5 50 ot-overhead vapcrs,-:yet-kettlem'oductsifrom which oxy emandaother contaminants and whichfa-re 'ceduresby which fractions-of anydesired boiling 'ralmost odorless. irange may-be Withdrawn :as skettletproducts, t-an'd octanevmotor fuel are:distilled to crem v tth highly bra-nched paraflins;whensuch largenuan-:wture "of high boiling yalkylates is ob ained as-tampparentlyithereactionscbyiwhich bhe cidorou .-=-=,without:any odorat-;all "but it-develop :disagree- -presencei'of dissolvedoxygeninvthezincoming feed itionscdf any :desired'laoilingcrange are vzdistilled o0 =tinuing ones. Under such:cimumstancesiodorous -*-!romfiresh, odorless :mixture the resultin prod cts-which arezsufiicientlvvolatile to hemari'listillates*are.found*tohaverancid,disagreeab d Onward y r he'-vaporxstreamiare rfoimedabut the industrles mentioned :above. 'fllhisisrue amoeb -deter ent frac ionation because =the= ;diswhether the-:distillation sis .zperformedibaltohwifi 1 $555 isolved msreenmmsem i Ithe omin ffi illi- Patented May 3, 1949 RBERARATION (OF ODOBLESSFRACTIONS .OF. HIGHLY BRANGHEDLPARAEEINS sfiartlesville,Qkla.,-"a.ssignors to Phillips Petrodeum Gompanmrra corporationofIDelaware Applicationseptembcr 17,iI945,"SerialN.o.' .61'6;930

Z'CIa'imS. (Cl. 196-4 3) I :2 This invention relates to improvements "in01"60I1tiIIIlOHSlYfi-81t atmospheric pressure, with -methods ofseparating mixtures of highly =steam,-or under vacuum.fbranched'para'fiin hydrocarbons into fractions f This unexpected resulthas led "to numerous *d'es'iredboiling range which are odorless orshaveunsuccessful attempts to remove the odor' from j-so little odor'asto-beunobjectionable when' such 1 such distillates. These have includedprocesses f-ractions are usedas solvents. of blowing the distillate-with'air,=blowing;:it'with In alkylation processes for the production 0fnitrogen, blowing it with carbon dioxide,=extract-*highoctane*motorfuels, wherein isobutane and 'i'ngthe'distillate'withalkali; refiuxing the distilip bjectfthe:feedstocksitotaveryil i :55 during the distillati0n 0f -such:mi-xturesofhigh1y fiegree of=purificationlin orderito:obtainrmaximum branched'pa-i'aifins are'present'in anycondensate results in syntheticr'hydrocarbon eproducts which large 'quantitiesof vapors have beenevolved are :are :almost entirely free from sill-fur, nitrogen,*freeiromodorya novel application'of known pm- *When the :productsresultin i'from 3631 53531171 'a-method for'producingdargerquantitiesofvapors alkyl i nprocesses "f r heiproduction o h than those evolved"by distillin the mixture ;;.of

ralkylates boiling :in zthergmotor :iuel range-a:mlxd5-tttiesdf-vapor:arezxdesirable.

kettle product. This by-ipr duc is aprac ioally .imaterialsare-formedinvolvexoxidation and -inthe 'nble 'o'dor on 'ag'ingyoroniboilina When flailstothe distillationsystemthese reactionsrarescon-'"o'rlorswhich make them-unfit: for'useras solventsin -odgrrcannot heieliminatcd i overhead Joy 4 increasnishes the condition essential forthe formation of additional odorous products. This is a theoreticalattempt to explain this unusual behavior of these hydrocarbons but we donot wish to con fine or limit our invention to any theory or mechanismof chemical action. We have found that under such conditions any out ofdistillate through which vapor passes, as it does on a plate of afractionation column, is odorous; while a kettle product from whichlarge quantities of vapors have been evolved is without objectionableodor.

Our invention may be better understood by reference to the accompanyingdrawing which shows diagrammatically one illustrative embodimentthereof.

A mixture of highly branched paraffin hydrocarbons such as thatrecovered as kettle product from the distillation of alkylates boilingin the motor fuel range is fed via line I to the first of a series offractionating towers. These fractionat ing towers 2, 0, l0, and I4 areoperated at progressively lower temperatures, and/or at successivelyhigher pressures.

From each fractionating tower of the series the overhead vapors areconducted via lines 3, l and I l respectively, to serve as feed for thetower oper ating at the next lower temperature, or higher pressure andare introduced into the medial portion of such next tower. A kettleproduct of desired boiling range is withdrawn from each tower via lines4, 8, l2, and [0, respectively.

It is obvious that the number of towers in this series may be increasedor diminished according to the number of cuts of product desired; andthat the towers may be operated at any series of successively lower endpoint temperatures or higher pressures that may be required. The fourend point temperatures illustrated merely indicate four commerciallydesirable cuts of product, when pressures in the towers areapproximately equal.

When it is desired to prepare a fraction having a boiling range below400 F. from a feed comprising the kettle product obtained by distillingofi products boiling in the motor fuel range from the total products ofan alkylation reaction it may be found that such feed does not containenough low boiling materials to produce sufficient vapors to carry theodorous materials oif overhead. In such case we have found that theintroduction of low boiling naphtha via lines 20 and 2i will furnishvapors sufficient to drive the odorous materials off overhead withoutimparting objectionable odor to the kettle roduct. The naphtha sointroduced is recovered as an odorous overhead product and may beconducted via line l5 to storage for any use where odor is notobjectionable.

It is obvious that naphtha of suitable boiling range may also beintroduced into any tower of the series wherein increased evolution ofvapors and/or increased vapor scrubbing effect may be found desirable.This may be accomplished by passing the naphtha through lines 25, 26,21, and/or 28 as indicated by the dotted lines.

Kettle products withdrawn via lines 4, 8, l2, and IE are practicallyodorless when freshly prepared. Upon boiling or prolonged aging theseproducts are found to develop odor. However, no further treatment isnecessary when these kettle products are to be used within a few months,and if they are to be stored for a longer time before use, thedevelopment of odor may be inhibited by any suitable means.

While in the description of the process we have emphasized itsapplication to the kettle product obtained by distilling ofl alkylatesboiling in the motor fuel range, it is obvious that our invention isapplicable to any mixture of high boiling, highly branched paraffins,however obtained. The highly branched character of the paraffin,associated with large numbers of tertiary and/or secondary carbon atoms,is all that is necessary to cause the overhead products to be odorousand the practice of our invention will result in desired fractions ofsuch paramns wherein the odors are unobjectionable.

It is also obvious that a single fractionating tower might be used wherethe object is merely to prepare an odorless fraction which has a desiredminimum boiling point when the upper limit of the boiling range is of nomoment.

The highly branched paramn hydrocarbon feed used in the presentinvention is commonly made by catalytic alkylation of low boilingisoparaifins with low boiling olefins employing a suitable alkylationcatalyst, generally with concentrated sulfuric acid or substantiallyanhydrous hydrofluoric acid. It may be made by alkylation of isobutanewith ethylene to give chiefly diisopropyl. This type of alkylation isgenerally effected with an aluminum chloride containing catalystpromoted with small amounts of hydrogen chloride. A method of preparingdiisopropyl in such manner is shown in the copending application ofClarence R. Ringham, Serial No. 556,208, filed September 28, 1944, nowPatent 2,409,389, issued October 15, 1946.

The term inert substantially odorless gas as used in this specificationrefers to any gas or mixture of gases which is substantially odorlessand which is inert insofar as reactions resulting in formation ofodorous compounds from highly branched paraffin hydrocarbons areconcerned.

We are aware that fractional distillation has been conducted in a seriesof fractionating towers in such manner as to yield fractions of desiredboiling range as kettle products prior to our invention.

We claim:

1. An improved process for producing an odorless branched-chain parafiinhydrocarbon fraction boiling from 350 to 400 F. from an olefinfreeparaflinic charge stock containing same and also higher-boiling andlower-boiling branchedchain parafiin hydrocarbons, said stock being freefrom sulfur and nitrogen contaminants and containing oxygen, whichcomprises subjecting such a charge stock to fractional distillation andremoving therefrom an odorous distillate comprising said desired 350 to400 F. fraction and lowerboiling parafiin hydrocarbons, introducing astream of said odorous distillate into an intermediate point of a,fractional distillation column, withdrawing from said column as adistillate an odorous stream of paraflin hydrocarbons boiling below 350F., and removing as a kettle product from said column an odorlessfraction boiling from 350 to 400 F. as a product of the process.

2. An improved process for producing an odorless branched-chain paraffinhydrocarbon fraction boiling from 350 to 400 F. from an olefinfreeparafiinic charge stock containing same and also higher-boiling andlower-boiling branchedchain parafiin hydrocarbons, said charge stockbeing free from sulfur and nitrogen contaminants and containing oxygen,which comprises subjecting such a charge stock to fractionaldistillation and removing therefrom an odorous distillate comprisingsaid desired 350 to 400 F fraction and lower-boiling paraflinhydrocarbons, introducing a stream of said odorous distillate into 5 anintermediate point of a fractional distillation REFERENCES CITED columntogether with a naphtha fraction which is The following references areof record in the sufficiently low-boiling to be recovered in theoverhead distillate fraction from said column, me of thls patentwithdrawing from said column as a distillate an UN TED STA ES PATENTSodorous stream of paraflin hydrocarbons boiling Numhm. Name Date below350 F., and removing as a kettle product 1 955 246 Link 17 1934 fromsaid column an odorless fraction boiling 1957818 Carney May 1934 from350 to 400 F. as a product of the process. 1:988:061 Wagner Jam 19352,111,259 Blengsli Mar. 15:1938

gfiggg Lggfggg 2,160,103 Kraft et a1. May 30, 1939 2,286,504 Parker June16, 1942 2,405,393 Atkins Aug. 6, 1946

